if a site does anything like this to me twice i no longer use that exchange or service. i tried playing at a crypto casino (which i won't promote, but the last 2 letters of their URL are: ag) and both times after requesting a withdrawal they waited until i contacted their support before they would actually process the withdrawal.  What if there's a crash in 10 minutes and i get word of it and want to sell before my coins are worth less, but instead they are frozen in an order on a site for whatever good reason?